I have problems during a downlink.
If the field “fCnt” is at “1” (I see it in the database “Postgresql”, table : “device_queue”) then the payload is sent to the device. However, if this is not the case, the payload is not sent.
In case of failure I find this in the “live lorawan frames”:

fCnt:0

fPort:null

frmPayload:null

PS: the use of fCnt (Downlink frame-counter) in the request API and/or MQTT not change anything.
PS2: I use data (Base64 encoded) not jsonObject

after upgrading loraserver v2.8.1 we have started 2 nodes of MAC v1.1.x but 1 nodes was not joining (problem with JoinAccept ack to node or rx2timeout issue)
it will working automatically after 2-3 min but another node was not working
in previous version of loraserver it will work
only 1 node was working at a time